FIG. 5 shows a configuration of one example of an existing image scanner.
An object capable of transmitting light, such as a film 4, is placed on light table 5 to be scanned. A light source built into light table 5 is turned on, causing the object to be scanned to be illuminated from behind. The light from the object to be scanned 4 passes through zoom lens 2 and is focused onto area sensor 1. In this way, the images on the object to be scanned 4, i.e., letters, figures, and so on, can be read by area sensor 1.
If the object to be scanned is a sheet of paper on which letters and figures are printed, the light emitted by light table 5 would be interrupted if the object were placed on the table. Instead, light sources 3 are lit, and their light illuminates the object to be scanned from above. The light reflected by the object to be scanned passes through zoom lens 2 and is focused onto area sensor 1. The angle of the field of view of zoom lens 2 is set to conform to the size of the page.
FIG. 6 shows another example of an existing scanner. The components of this scanner which have counterparts in FIG. 5 have been given the same reference numbers, and will not be again described. In this scanner, line sensor 11 is used as the sensor, and an interchangeable lens 12 is used as the lens. All other components are identical to those of the scanner in FIG. 5.
Line sensor 11 can read only the images on a given line, one line at one time. For this reason, object 4 is scanned in the additional direction indicated by arrows in FIG. 6. This allows the scanner to read all the images contained on object 4. Interchangeable lens 12 can be replaced so as to achieve a given resolution when an object to be scanned 4 is changed from a film to a printed page or vice versa.
As described above, existing image scanners deal with the problem of scanning objects with different resolution by readjusting the angle of the field of view of zoom lens 2, each time the resolution is changed, or by replacing the lens 12. These methods have problems when a variety of objects need to be scanned, as it consumes a great deal of time to change the equipment to accommodate the type of object to be scanned.